A dam that for years has blocked fish and kayakers from moving freely in a major tributary of the Congaree River will be torn down, marking one of the few dam removals ever conducted in the Columbia area.
The U.S. Fish and Wildlife Service plans to start dismantling the metal structure Tuesday at Congaree Creek, the agency said. Eliminating the dam, which should take several days, will allow fish to swim upstream to spawn, while making the stream flow more smoothly for paddlers. Canoeists and kayakers interested in paddling upstream will no longer have a dam blocking them.
But as much as anything, tearing down the small dam at Congaree Creek is a symbolic victory for river protection advocates who favor removing more outdated and unnecessary dams across the state and nation. Efforts have intensified across the country in the past 20 years to dismantle dams that have outlived their purposes.
The Congaree Creek dam removal results from collaboration by environmental groups, federal and state agencies, and the city of Cayce.
“All dams have impacts to our natural ecosystems and our rivers that fish and wildlife depend on,’’ said Gerrit Jobsis, a regional official with the environmental group American Rivers. The question in deciding to remove a dam is whether the structure is “causing more impacts than the benefits it is providing,’’ he said.
In South Carolina, a dozen dams are known to have been removed, with most occurring since 1979. That includes two in the Columbia area prior to the Congaree Creek project, according to federal data provided by American Rivers.
The Fish and Wildlife Service has taken down more than 20 dams from Virginia to Texas in recent years to restore natural creek and river flows, said the agency’s Tripp Boltin, who is working on the Congaree Creek dam removal project. In South Carolina, the agency now is working on another dam removal project in the mountains of northern Greenville County.
Last year, 82 dams were removed across the country, according to American Rivers.
Congaree Creek runs from the interior of Lexington County through a S.C. Department of Natural Resources’ nature preserve, before emptying into the Congaree River near Cayce. Thick forests line much of the stream, which is inhabited by a variety of fish, as well as alligators. The creek is a key feature of the popular preserve.
The dam at Congaree Creek rises about five feet above the water near a small bridge on U.S. 321 outside Cayce. The structure has not only frustrated paddlers, but a property owner upstream complained that water was backing up because of the dam and flooding his land, officials said.
Next week’s removal project is not related to damage from recent hurricanes and floods, which washed out dams and left piles of debris in creek beds, according to American Rivers. Some of that debris has been removed and the dams were not rebuilt.
Still, removing dams voluntarily can save people from legal liability and headaches if a dam broke during the next major storm, Jobsis said.
Fish that should benefit from the dam removal include blueback herring, American eels, sunfish and several types of shiners. Paddlers who want to put their boats into Congaree Creek will find the water calmer at an access point just below where water spilled over the dam, said Congaree Riverkeeper Bill Stangler.
One issue that needed thorough study was whether pollution would be released into lower Congaree Creek after the dam is removed. Dams create lakes or ponds that sometimes keep pollution from washing downstream. In effect, the lakes become sinks for pollution that could be released if a dam is removed.
A chemical that is deadly to fish spilled in the Red Bank Creek-Congaree Creek area nearly 20 years ago, sending a slug of the toxin downstream. The chemical, tributyltin, killed fish and kept ponds off limits for swimming for years in parts of Lexington County. Traces of tributyltin also were found in the Congaree River.
But recent studies by the federal government show that none of the pollution is lingering upstream of the Congaree Creek dam. The tin material did not stick to the sandy sediments on the creek bottom, meaning it appears to have all flushed through the system. That in turn allowed the dam removal to go ahead, Jobsis said.
The Congaree Creek dam in Lexington County was built in the 1950s to provide a backup drinking water supply for the city of Cayce. But Cayce, which has a gleaming new water plant, doesn’t need the backup supply — or the dam. American Rivers, the state Department of Natural Resources, the Congaree Riverkeeper, the Fish and Wildlife Service and the city of Cayce have been working on the removal plan for about three years. American Rivers spearheaded the effort.